ClangFormat: Fix compiliation with LLVM19

Change-Id: I4b166da2e477ffd101a5c4b9aa07c710f7698da9
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformatbaseindenter.cpp

@@ -65,7 +65,11 @@ static void adjustFormatStyleForLineBreak(clang::format::FormatStyle &style,
 
 static llvm::StringRef clearExtraNewline(llvm::StringRef text)
 {
+#if LLVM_VERSION_MAJOR >= 16
+    while (text.starts_with("\n\n"))
+#else
     while (text.startswith("\n\n"))
+#endif
         text = text.drop_front();
     return text;
 }

src/plugins/clangformat/llvmfilesystem.h

@@ -127,7 +127,11 @@ public:
     /// Gets real path of \p Path e.g. collapse all . and .. patterns, resolve
     /// symlinks. For real file system, this uses `llvm::sys::fs::real_path`.
     /// This returns errc::operation_not_permitted if not implemented by subclass.
-    std::error_code getRealPath(const Twine &Path, SmallVectorImpl<char> &Output) const override
+    std::error_code getRealPath(const Twine &Path, SmallVectorImpl<char> &Output)
+#if LLVM_VERSION_MAJOR < 19
+        const
+#endif
+        override
     {
         Q_UNUSED(Path);
         Q_UNUSED(Output);